The present disclosure herein relates to integrated circuit devices and methods to manufacture the same and, more particularly, to semiconductor memory devices and methods to manufacture the same.
Generally, integrated circuit semiconductor memory devices may be classified as volatile or nonvolatile memory devices. A volatile memory device loses stored data when the power supply is interrupted. Volatile memory devices include, for example, dynamic random access memory (DRAM) and static random access memory (SRAM) devices. A nonvolatile memory device maintains stored data even when the power supply is interrupted. Nonvolatile memory devices include, for example, programmable ROM (PROM), erasable PROM (EPROM), electrically EPROM (EEPROM) and flash memory devices.
As the electronic industry develops further, further increases of integration density of semiconductor devices may be needed. However, if semiconductor devices are simply integrated by scaling down, various problems may occur. For example, if a minimum width of a semiconductor device is reduced to several tens of nanometers, margins of manufacturing processes of the semiconductor device may be reduced. Also, it may be difficult to optimize and/or match different characteristics of various elements (i.e, driving circuits and/or memory cells) respectively performing various functions in the semiconductor device.